The water-soluble Rh-1-THP complexes: RhCl(1,5-cod)(THP) (1), [Rh(1,5-cod)(THP)(2)]Cl (2), RhCl(THP)4 (3), and trans-RhCl(CO)(THP)(2) (4) have been synthesized and characterized, where THP = P(CH2OH)(3); 1-3 are the first potentially useful entries into Rh-1-THP chemistry, while 1 and 4 are the first structurally characterized Rh-1-THP complexes.